1. Technical Field
The invention relates to the transfer of information across a plurality of dissimilar display devices. More particularly, the invention relates to a generic information interface architecture for transferring display information from a server to a plurality of dissimilar display devices, thereby allowing the server to ignore the attributes of each particular display device.
2. Description of the Prior Art
Computer system applications that require user interaction communicate information through devices such as Liquid Crystal Displays (LCDs), Light Emitting Diode (LED) displays, plasma displays, and cathode ray tubes (CRTs). Each display type requires a specialized driver to control any graphical representations on the display. The graphical representations may be very simple, one-line messages, e.g. xe2x80x9cSelf Test,xe2x80x9d to very complicated graphical user interfaces (GUIs).
A software developer must create source code that is custom tailored for each display with which his application communicates. Typically, a library is created that represents all of the allowable graphic primitives on the screens that are displayed on the chosen display. The library contains information such as the screen creation primitives, button labels, user messages, blink characteristics, and headings. Built on top of the library is a module containing all of the screen descriptions. The library and screen description module are written in the programming language, e.g. xe2x80x9cC,xe2x80x9d that the software developer is using and customized for the type of display, e.g. a one, two, or five-line LCD display, or a GUI display. The differences between a two-line and a five-line LCD display is the amount of information that can be displayed. A two-line LCD display is limited in the amount of text that can be displayed to the user as compared to a five-line LCD display. A GUI display has much more display area than a line-limited LCD display. It can display on one screen, information that would require several screens on a line-limited LCD display. The source code is then compiled with the application source code and delivered as part of the final product.
This hard coding of display screens requires that new source code be created and compiled into the application software whenever a new display device is selected. The source code for each display type must be archived and maintained for the life of each display device. This is a cumbersome and expensive task, e.g. there are N different source codes for N different display devices used.
U.S. Pat. No. 4,787,035 issued to Bourne on Nov. 22, 1988, discloses a system which uses an interpreter that examines messages using grammar and lexical tables to produce a parse table. The parse table is compared to data needed in a semantics table to fire a rule which causes a function table to be evaluated and performs user desired functions. This is particularly suitable for manufacturing systems with multiple target languages.
If the product is one that is used by an Original Equipment Manufacturer (OEM), the OEM usually requires custom displays to differentiate their product from the other OEMs using the same base application. For an OEM engineer to create his custom displays, he must know the internal structure of the application""s software. Revealing such information is many times a sensitive issue. The originating company would prefer to keep such internal software structures confidential in an attempt to retain their value as a product supplier to any OEM.
It would be advantageous to provide a display interface system that allows the developer to create a single set of screen descriptions that is used for all supported display types. It would further be advantageous to provide a display interface system that is independent of the display location, i.e. whether the display is embedded in the system or network accessible.
The invention provides a display interface system that has a generic architecture and is thereby independent of the supported display type. The invention uses a generic language approach that is independent of the type of display chosen and its location in relation to the generic code generator.
The invention uses a server-client approach. The server contains all of the necessary information regarding display information, while the client deals with the specific display type to which it is connected. The server allows a software developer to create generic descriptions of user interface screens. The generic screen descriptions allow the server to be independent of specific display types. This allows one version of software to support many types of displays, rather than several software versions for each display type. The software developer saves on time, maintenance, and labor costs.
A request-response communication system is used whereupon the client, acting as the user interface, requests previous or next user display screens, system parameter requests or updates from the server. Thus, the user interface function is offloaded from the server. The client requests screen information through a series of key-tag sequences. User display screen sequencing is controlled by the server. The concept of user display screens is known only to the server. The client is shielded from any knowledge of the contents of the screen and is only concerned with the fact that something is being displayed.
Communication between the server and client is through a unified protocol. The server-client approach, combined with the unified protocol, allows the client to be located either locally, in the same machine or remotely, across a network.